The invention relates to a process for an apparatus for automatic matching of raw lenses, produced in accordance with order data, to a predetermined spectacle frame and for machining the edges to produce an accurate fit, by means of at least one CNC-controlled spectacle lens edge-machining machine, which has an input interface, having the following steps: the PD values for the left and right eyes are entered into a computer in accordance with the order data, the center height for the left and right eyes is entered in the computer in accordance with the order data, the optical values of the left and right eyes are entered in the computer in accordance with the order data and, if provided, the position of a reading section or of an intermediate corridor is entered in the computer, the raw lens diameter and the position of the optical center point and/or the raw lens dimensions are entered in the computer if the raw lenses are not round, and the position of the optical center point is entered in the computer with reference to the geometric center point for raw lenses which have been decentered in advance, are circular or are not circular, the shape data of the frame edges of the predetermined spectacle frame is entered in the computer, the shape data of the left and right spectacle lens openings and of the left and right raw lenses, which have been aligned in accordance with the PD values, the centering height of their respective optical center point, the axis position of a cylindrical component and/or the base position of a prismatic component of the optical effect, and, if given, with respect to the position of a reading section or of an intermediate corridor, is superimposed by calculation by the computer, the computer checks by calculation whether the size of the raw lenses is adequate for edge machining to match the predetermined spectacle frame.
Processes such as these and the use of the corresponding apparatuses are disclosed in DE 198 04 542 C2, EP 1 366 857 B1 and DE 100 13 648 A1.
The following principles for optical spectacle matching are described in the textbook: Dr. Enders, Die Optic des Auges und der Sehhilfen [The optics of the eye and vision aids], ISBN 3-9269-36-2, pages 4 to 69.
In order to machine the edges of spectacle lenses by means of CNC-controlled spectacle lens edge-machining machines, it is necessary to take account of the data relating to the individual and the data relating to the frame. The data relating to the individual includes the distance between the pupils of the eyes of the spectacle wearer (PD value) the optical values of the left and right spectacle lenses and, if given, details about the position of a reading section or of a varifocal corridor for varifocal spectacle lenses. The data relating to the frame includes the overall or the individual distance between the eyes (distance between centers), the height differences of the pupils of the left and right eyes (height centering), the corneal vertex distance, with respect to the selected spectacle frame, the angle of forward inclination of the spectacle frame and the frame bending (frame horizontal inclination angle). The data is referred to in a summarized form in the following text as the order data.
The required raw lens diameter can be determined from these values and in conjunction with the dimensions of a selected spectacle frame, and this need not necessarily be the same for the left and right spectacle lenses, although this is preferable.
For simple spectacle lenses with a low dioptric strength, in which the optical center point coincides with the geometric center point of the raw lens, it is generally possible to find a minimum raw lens diameter which is suitable for grinding the shape of the spectacle lenses intended for a predetermined spectacle frame, and this requires as little edge machining work as possible. In the case of positive lenses, this also results in the minimum center thickness. This is particularly true when the distances between the pupils of the eyes of the spectacle wearer and the spectacle frame center are essentially the same, there is very little height difference, or no height difference at all, between the left and right pupils, and when the vision strengths of the eyes are the same or are only slightly different. This is the ideal case, which also presupposes spectacle lenses with an ideal geometry.
If, for weight reasons, positive lenses with an optimized center thickness and therefore sharp edges and with a strong dioptric effect are intended to be fitted into large or broad fashionable spectacle frames, leading to unusual decentering values, in order to achieve spectacle lenses that are thin and light, it is frequently necessary to use raw lenses whose optical center point differs from the geometric center point, so-called predecentered raw lenses, which, in addition, may also not be round.
If these spectacle lenses also have different optical values for the left and right lenses, different, asymmetric axis positions of the cylindrical or prismatic component, different distances between the pupils and the spectacle frame center on the left and right, and also significant height differences between the left and right pupils, it is extremely difficult to define the correct raw lens diameter for the left and right spectacle lenses and to fit them in, taking into account the tolerances with respect to the vertical fusion width and the fusional divergence and convergence capability of the spectacle wearer.
Optical technicians working in the commercial field admittedly have the experience and the skill to find a compromise between the various, in some cases contradictory, requirements, but it is not always possible to avoid the fitting process failing or the lens breaking, or for good compatibility of the spectacles not to be achieved, thus resulting in the aim of automating the entire process of matching spectacle lenses produced in accordance with order data to a predetermined spectacle frame and the process of machining edges with an accurate fit, and to move this to large concerns in order in this way to avoid errors and to make the process of fitting the spectacle lenses more economical.
EP 0 379 427 A2 discloses a semi-automatic process and an apparatus for matching spectacle lenses produced in accordance with order data to a predetermined spectacle frame, and for machining the edges by means of a CNC-controlled spectacle lens edge-machining machine.
This process and the corresponding apparatus result in a raw lens which has been clamped in a spectacle lens holding shaft of a spectacle lens edge-machining machine being scanned on both sides by means of sensors along the circumference of the finished lens, corresponding to the predetermined spectacle frame. If these sensors go beyond an area of the circumference of the clamped-in raw lens, this means that the raw lens is too small in this area. The computer which controls the apparatus is programmed such that it can automatically calculate a movement of the finished lens contour such that it is located entirely within the circle of the raw lens. The magnitude of the computed movement is indicated, and the operator decides whether the movement magnitudes are satisfactory and, if this is the case, the machining process is initiated, based on the new values, by pressing a button. This process is carried out successively for a left and a right spectacle lens in each case, although the corrections which may be carried out are not related to one another in any way. In addition, this document does not contain any details on the criteria which the operator uses to assess whether the correction values are satisfactory, and the optical values of the spectacle lenses are ignored.
Furthermore, DE 41 26 313 A1 describes a CNC-controlled spectacle lens edge grinding machine which has a measurement device for measuring the distance between the geometric centers of the frame edges of a predetermined spectacle frame, an input device for entering a previously measured distance between pupils, a calculation device for calculation of any setting amount which occurs or is apparent from the difference between the distance between the pupils and the distance between the geometric centers of the spectacle lens openings of the spectacle frame, and a correction device for correction of the setting amount which occurs or is apparent on the basis of the curvature of the front surface of the spectacle lenses to be machined, the three-dimensional data relating to the spectacle frame, and the V-groove curve or curvature. This apparatus can be used for corrections for spectacle frames with large dimensions and with a large amount of curvature and angular discrepancy on a vertical plane. The measurements are either carried out both at the left and at the right edge of the frame of the spectacle frame, or they are carried out only on one frame edge, on the assumption that the two frame edges are congruent, in mirror-image form, in which case the measured data is inverted by calculation for the other frame edge.
The data for the left and right spectacle lenses are not related to one another, the optical values of the spectacle lenses are ignored, and there is no check of whether the raw lens diameter is sufficient to use this raw lens to produce the spectacle lenses required for the predetermined spectacle frame.
Checking whether the raw lens diameter is sufficiently large for a given shape of the finished lens taking into account the decentering values and if appropriate including corrections, is closely linked to the general requirements for matching the spectacle lenses to a spectacle frame chosen by the spectacle wearer.
The general aim is that the points at which the spectacle wearer looks through the spectacle lenses should coincide with the corresponding centering reference points, for example the optical center point, on the spectacle lenses. The corresponding geometric values are the distance between the center points and the centering height of the spectacle wearer. In addition to achieving optimum vision, a further aim is good compatibility with the spectacles. This is because undesirable prismatic effects occur if the centering reference points are not related. The brain can compensate for this within certain limits. In this case, incompatibilities can occur such as fatigue, headaches or visual disturbances in the form of double vision, if the forced compensation is not achieved by eye adjustment. The movement apparatus for the eyes can carry out specific movements which allow incorrect prismatic effects to be compensated for. For example, the fusional convergence capability is considerably greater than the fusional divergence capability, since the viewing axes of the eyes for long-distance vision must be very highly parallel, but never diverge, and do converge for short-range vision. A horizontal outward prism can therefore be compensated for by convergence of the vision axes, but compensation of an inward prism is very poor since the movement apparatus does not allow the vision axes to diverge outwards.
In the same way, vertical prisms in the same sense can be compensated for without any problem, since the movement apparatus of the eyes carries out the parallel movement of the vision axes upwards and downwards without any problems, but has difficulties in moving the two eyes in opposite directions.
The greater the dioptric effect of the spectacle lenses, the less is the permissible centering error, with a fixed prismatic tolerance limit. This results in the accuracy requirements for centering, which are greater the higher the induced, that is to say inadvertent, prismatic effect of the spectacle lenses. Vertical prismatic effects in opposite senses should be avoided, that is to say the centering reference points should be achieved as accurately as possible for the centering height. Centering error discrepancies in the case of negative lenses can be tolerated to a lesser extent outwards, and more inwards, while they can be tolerated less inwards, and more outwards, with positive lenses.